Thursday, September 25, 2008

Refastening Plan or Schedule for Wood Boats

OBSERVATIONS, DISCOVERIES, and FINDINGS

Acting upon the request of Mr Smith, the undersigned inspected underbody and topside fastenings of a Chris Craft yacht while it was blocked up at Boat Yard on 2008. Parties present at the time of inspection were Mr. Jones (shipwright) and the undersigned. The purpose was to make a better determination of the general condition of the hull fastenings and propose a refastening schedule.

With the aging of the fleet, as with most mid-century wood yachts (and small craft), the serviceability (viz., fitness for intended usage) of original metal hull fastenings has reached an observable end point. This event is not unexpected but rather expected given the nature of wood boat fastenings and should be dealt with in a systematic and prudent manner to preserve the seaworthiness of the vessel while not inflicting undue damage during restoration. This is particularly true with vintage Chris Craft yachts.

Regarding the subject vessel, numerous hull fastenings were opened up and or inspected along the waterline, garboard, and broad planks and on the transom – hood plank ends. In addition, since the last inspection, the vessel’s starboard topsides (amidships and aft) have been (nearly) stripped of all paint - down to bare wood from the waterline to the sheer. This allowed for a clear observation of the original fastening pattern and the nature - extent of previous refastening work. In addition, some underbody paint was removed to reveal additional exterior hull fastenings Based on these observations we can now address some of the concerns raised in the original survey report.

“The undersigned concluded the vessel has been subject to fastener wastage for some time and previously undergone some refastening (the extent and degree unknown at this time).” - We now know that this is indeed clearly the case. It would appear that approximately twenty (20%) percent of the exterior hull fasteners (found on the topsides and on the underbody) have been replaced (at an unknown date – evidenced by being bunged with a hard, dark colored, epoxy-like material rather that the original soft – white bung compound commonly used by Chris Craft). In addition, the replacement fasteners are Philips (head) bronze wood screws and not the original Reed-Prince bronze wood screws. The existing re-fastening pattern seems somewhat capricious (probably based on temporal needs), but never-the-less represents a material refastening of both planks (on frames) and (seam) battens. The condition of these fasteners is good and very serviceable.

“No proud or rattling planks were observed. The seams visually appeared to be tight and stable.” – When initially inspected, the undersigned found only a very small amount of bilge water – a clear indication of hull tightness and garboard stability. In addition, since the time the vessel has been hauled and blocked (out of the water nearly three (3) weeks), very little, if any, movement, cracking, or material changes in the seams, frames, timbers, and or butts was observed…a good indication of the integrity of the existing hull fasteners. To be sure – as indicated in the original report, “In general, a substantial amount of the removed fasteners were found to be in serviceable condition with sharp pitch showing little, if any alloy break-down (and tightened up well when replaced).”

“A fair amount of the fasteners (approximately 25 - 30%) where found to have moderate to serve alloy break down with one (1) unserviceable fastener replaced with a new bronze fastening). Some screw heads are soft and brittle, and three screw heads partially broke off, while attempting to remove the fastener. The scope and location of suspect fasteners varied but generally the portside underbody from the garboard plank up to and slightly above the waterline produced the greatest amount of suspect fasteners.” – Regardless of past refastening work and the number of still serviceable fasteners, a fair amount of the existing fastenings are at the end of their serviceable life and in need of replacement. When dissimilar metals are in damp, salt-water wet wood they become electrically connected and corrosion occurs. With unserviceable bronze fasteners, the metal becomes pink in color and brittle, and only those would be renewed. Generally speaking, the majority of (potentially) wasted fasteners should be found amidships and aft on the quarters (underbody, transom, and topsides up to about one (1) foot above the waterline). It was originally contemplated by the undersigned that a schedule to include immediate sister fastening with a delayed king frame refastening schedule was possible…but now, given the fact that the vessel’s topsides are being taken to bare wood in preparation of painting, an opportunity to refasten (with minimum damage to the vessel) presents itself.

Based on the information presented herein regarding the scope and number of observed existing replacement fasteners and the extent of observed unserviceable fasteners, the following re-fastening schedule is recommended. The undersigned reserves the right to revoke, amend, modify and or revise any and all recommendations and conclusions found herein and elsewhere based upon subsequent discoveries and or observations.

REFASTENING SCHEDULE:

It is recommended that the following specific exterior original hull fasteners (not those used in previous refastening work) be replaced - renewed (a section at a time) while the vessel is presently hauled and blocked:

Starting amidships (both port and starboard sides) then aft and forward, commence (plank on) king frame and butt block refastening beginning about one (1) foot above the waterline and continue down to the garboard plank at the keel. Open up and replace existing original and or wasted hull fasteners with same size (approximately #8) and correct length marine-grade bronze wood screws. Over-size fasteners should be used those instances when a new fastener will not properly tighten up. Sister fastening should be used when an existing fastener cannot be removed without causing damage to the wood hull – frame structure. A sister fastener should be fitted when it does not compromise the adjacent wood structure, (that is – to cause cracking, splitting, or create a weak spot in the plank, butt block, and or king frame).

Suspicious original batten fasteners should be opened up, inspected, and replaced when in question vis-à-vis wasted adjacent frame fastenings. As required, replace existing original and or wasted hull fasteners with same size (approximately #8) and correct length, marine-grade bronze wood screws. Over-size fasteners should be used in those instances when a new fastener will not properly tightened up. Sister fastening should be used when an existing fastener cannot be removed without causing damage to the wood hull structure. A sister fastener should be fitted when it does not compromise the adjacent wood structure,

The original transom planking fasteners should be opened up, inspected, and replaced from about one (1) foot above the waterline and continuing to down to the bottom of the transom. Replace existing original and or wasted fasteners with same size (approximately #8) and correct length marine-grade bronze wood screws. Over-size fasteners should be used in those instances when a new fastener will not properly tightened up. Sister fastening should be used when an existing fastener cannot be removed without causing damage to the wood hull – frame structure. A sister fastener should be fitted when it does not compromise the adjacent wood structure.

The hood plank end (original) fasteners should be should be opened up, inspected, and replaced from about one (1) foot above the waterline and continuing downward. Replace existing original and or wasted fasteners with same size (approximately #8) and correct length marine-grade bronze wood screws. Over-size fasteners should be used in specific instances when a new fastener will not properly tightened up. Sister fastening should be used when an existing fastener cannot be removed without causing damage to the wood hull – frame structure. A sister fastener should be fitted when it does not compromise the adjacent wood structure.

Only new, marine grade bronze fastenings should be used. The use of dissimilar metal fasteners is strongly discouraged and must be avoided. Fastener openings should be completely and securely plugged with either glued mahogany bungs (slicked clean, filled, and faired) or sealed - faired with a marine grade underwater seam compound to protect fastenings and restore proper cosmetic appearance.

In the event that a section of good serviceable original hull, topsides, or transom fasteners is found and documented (for example, working from an area of non-serviceable fasteners into an adjoining area where the vast majority of existing fasteners are visually free of wastage and alloy break down), then scheduled refastening may be dispensed with in that specific area only. All fasteners (as specified herein) must be renewed unless determined otherwise by a competent shipwright and or marine surveyor.

In the event that damaged, soft, weakened, or decayed (rot fungi) wood is discovered, the nature and extent of which must be determined. Any replacement or repair to existing wood structure(s) should be reviewed by a competent shipwright.

Written and photographic documentation regarding the location - condition of existing, new, and remaining fasteners (frame and plank number) along with any relevant observation regarding the condition of the wood structure should be kept and preserved for future reference. Old fasteners should be retained for inspection.

All work must be carried out in accordance with accepted marine construction practices, with demonstrable good craftsmanship, and with due regard to the nature, scope, and importance of maintaining the seaworthiness of the vessel.

The completion of the proposed fastening schedule does not relieve any obligation or requirement to dispense with regular fastener inspections and or future refastening due to on going fastener wastage. All Observations, Non-Standard Conditions, and Recommendations contained in the original survey report remain in effect.

The opinion and report herein is given without prejudice to the questions of rights, interests, and or liabilities on the part of any and all persons concerned.